This invention relates to radar systems, and in particular to methods of operation thereof that overcome the effects of certain backscatter ambiguities due to unknown target aspect angle.
When a radar system transmits and receives with fixed polarization and the target is at an unknown aspect angle the orientation of the E and H field vectors (polarization) with respect to the target are unknown. The amplitude and phase of the return depends on the orientation of the field vectors with respect to the target; thus if the target is illuminated with a radar with fixed polarization there is an uncertainty or ambiguity in the information contained in the amplitude and phase measurement made by the radar system for that target.
The quality of radar return signal can be improved by aligning the polarization of transmitted signals with the major axis of a target. Also, in radar applications in which target identification is an object, determination of the orientation of a target major axis is of primary importance. Substantial improvement in the performance of certain radar systems can therefore be achieved by eliminating such polarization ambiguity effects. The present invention is directed toward methods of radar system operation that effectively accomplish this end.